Pete, you should NEVER press fittings onto closed end pens, especially wooden ones. You're putting major stress through the unsupported closed end. DAMHIKT - I could show you a few of my early ones that look similar to this one! Put the centreband fitting into your chuck and take a very light skimming cut with a parting tool over the area that goes into the tube. What you are aiming to achieve is a slip fit into the tube. Then use epoxy to fit the component. (I wouldn't use CA, too risky.)
Pity - that would have been a beautiful pen!